John Montgomery, of the University of Auckland's Leigh Marine
Laboratory and School of Biological Sciences, responded.

Hammerheads help these sharks find and catch prey.

Fish (the prey for the sharks) generate electric fields. Sharks
detect the electric field, and hence the prey, with sensors lodged
in head pores. The hammerhead shape provides a wider head area and
correspondingly more sensors than other sharks have. So, hammerheads
pick up prey signals better.

The wing-like hammerhead also provides hydrodynamic lift so hammerheads
can turn tighter and faster. Prey has a tougher time losing the
hammerhead than other sharks.

Note that the eyes are further apart too, as are the nostrils and
they this conceivably would provide some other sensory advantages.

The trouble with these speculations is that they are just that -
there are no real scientific studies documenting the extent to
which hammerheads may or may not be better at prey detection or
capture because of their head.

One other alternate view is suggested by one observation of hammerhead
sharks feeding on stingrays. The hammer-shaped head may be directly
useful in prey handling. The shark used its head to `pin' a fleeing
stingray against the bottom and then `pivoted' its body into position
to deliver an immobilizing bite to the ray's pectoral disc.

To scientifically provide an answer to the question of the shape of
a Hammerhead shark's head, one really needs to demonstrate a specific
advantage that accrues from the head shape and to show that that
functional advantage was instrumental in the evolution of the head shape.
I think it is fair to say that we haven't met those requirements yet
in providing and authoritative answer to the question.